Systems and Methods for Tracking Multiple Collocated Assets

ABSTRACT

Systems and methods for locating collocated assets in accordance with embodiments of the invention are disclosed. In one embodiment of the invention, an asset tracking device includes a processor, a memory connected to the processor, and a communications device connected to the processor, wherein the processor obtains asset signal data, where the asset signal strength data includes asset data identifying an asset, calculates asset signal strength data based on the obtained asset signal data, and determines chained asset data based on the asset signal data and the asset signal strength data, where the chained asset data identifies a set of assets chained to a master asset associated with the asset tracking device.

CROSS REFERENCE TO RELATED APPLICATIONS

The current application is a continuation of U.S. patent applicationSer. No. 15/373,277 entitled “Systems and Methods for Tracking MultipleCollocated Assets” to Peter Hergesheimer, filed Dec. 8, 2016, thedisclosure of which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to determining location and morespecifically to determining the location of an asset.

BACKGROUND

A Global Positioning System (GPS) is a space-based global navigationsatellite system that utilizes a network of geo-synchronous satellitesthat can be utilized by a GPS receiver to determine its location. Manytelematics systems incorporate a Global Positioning System (GPS)receiver that can be used to obtain the location of a vehicle at acertain measured time. Using the signals received by the GPS receiver,the heading information of the vehicle can be determined. A GPS receivercan determine velocity information in a variety of ways including, butnot limited to, measuring the Doppler shift of the received signals andby comparing the location of a vehicle at a plurality of measured times.The acceleration of the vehicle can be determined as the change in speeddivided by the time between the measurements. A GPS receiver's abilityto determine acceleration can be limited due to the dependence of themeasurement upon factors such as, but not limited to, reception andsatellite availability. In addition to location information, a GPSreceiver can also be configured to provide time data. However,measurements determined via a GPS receiver can contain errors thataffect the accuracy of the measured information. In particular, GPSsignals are vulnerable to signal delays, inconsistencies of atmosphericconditions that affect the speed of the GPS signals as they pass throughthe Earth's atmosphere, and multipath distortions. Additionally, otherfactors not listed above can influence GPS signals and result inmeasurement errors.

Telematics is the integrated use of telecommunications and informatics.Telematics units are installed in vehicles to provide a variety oftelematics functionality in the vehicle. This functionality includes,but is not limited to, emergency warning systems, navigationfunctionality, safety warnings, and automated driving assistance.Telematics units are also capable of recording data related to theoperation of the vehicle and providing that information for analysis,whether in real-time or during a time when the vehicle is beingserviced. This information can be used in a variety of applications,such as fleet tracking, shipment tracking, insurance calculations, andin vehicle management and service.

SUMMARY OF THE INVENTION

Systems and methods for locating collocated assets in accordance withembodiments of the invention are disclosed. In one embodiment of theinvention, an asset tracking device includes a processor, a memoryconnected to the processor, and a communications device connected to theprocessor, wherein the processor obtains asset signal data, where theasset signal strength data includes asset data identifying an asset,calculates asset signal strength data based on the obtained asset signaldata, and determines chained asset data based on the asset signal dataand the asset signal strength data, where the chained asset dataidentifies a set of assets chained to a master asset associated with theasset tracking device.

In yet another embodiment of the invention, the processor determines thelocation of the asset relative to the asset tracking device based on theasset signal strength data.

In an additional embodiment of the invention, the asset tracking devicefurther includes a location determination device connected to theprocessor and the processor further determines absolute location datausing the location determination device.

In yet another additional embodiment of the invention, the processorfurther determines the absolute location of the asset based on theabsolute location data and the asset signal strength data.

In still another additional embodiment of the invention, the processorfurther transmits the chained asset data to a remote server system usingthe communications device.

In yet still another additional embodiment of the invention, thecommunications device includes a cellular modem.

In yet another embodiment of the invention, the communications deviceincludes a radio frequency transceiver and the asset signal data isreceived using the communications device.

In still another embodiment of the invention, the radio frequencytransceiver includes a Bluetooth Low Energy radio.

In yet still another embodiment of the invention, the asset signal datafurther includes synchronization data and the processor determines thechained asset data based on the synchronization data.

In yet another additional embodiment of the invention, thesynchronization data includes brake lighting system voltage data.

In still another additional embodiment of the invention, thesynchronization data includes counter data.

In yet still another additional embodiment of the invention, the assettracking device includes a diagnostic connector and the asset trackingdevice is connected to a vehicle diagnostic connector in an asset.

Yet another embodiment of the invention includes an asset trackingsystem including a set of asset tracking devices, wherein each assettracking device includes a processor, a memory connected to theprocessor, and a communications device and wherein at least one assettracking device in the set of asset tracking devices transmits assetsignal data, obtains asset signal data from at least one asset trackingdevice in the set of asset tracking devices, determines aggregate signalstrength data for each of the other asset tracking devices in the set ofasset tracking devices based on the obtained asset signal data, andcalculates asset position data for every other asset tracking device inthe set of asset tracking devices based on the aggregate signal strengthdata.

In yet another additional embodiment of the invention, each assettracking device in the set of asset tracking devices is associated withan asset, each asset tracking device in the set of asset trackingdevices is connected to a synchronization signal on its associatedasset, and the asset signal data includes synchronization datadetermined based on the synchronization signal.

In still another additional embodiment of the invention, a master assettracking device in the set of asset tracking devices further includes alocation determination device and the master asset tracking devicedetermines absolute position data describing the location of the masterasset tracking device using the location determination device anddetermines asset position data describing the location of the otherasset tracking devices in the set of asset tracking devices based on theabsolute position data and the asset position data.

In yet still another additional embodiment of the invention, the masterasset tracking device further transmits the asset position data to aremote server system.

In yet another embodiment of the invention, the communication deviceincludes a low power radio frequency transceiver and each asset trackingdevice in the set of asset tracking devices transmits the asset signaldata using the communications device.

Still another embodiment of the invention includes a method fordetermining the location of an asset including obtaining asset signaldata using an asset tracking device, where the asset signal strengthdata includes asset data identifying an asset and the asset trackingdevice includes a processor, a memory connected to the processor, and acommunications device, calculating asset signal strength data based onthe obtained asset signal data using the asset tracking device, anddetermining chained asset data based on the asset signal data and theasset signal strength data using the asset tracking device, where thechained asset data identifies a set of assets chained to a master assetassociated with the asset tracking device.

In yet another additional embodiment of the invention, the methodfurther includes determining relative location data for the asset basedon the asset signal strength data using the asset tracking device.

In still another additional embodiment of the invention, the methodfurther includes transmitting the chained asset data to a remote serversystem using the asset tracking device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual illustration of an asset tracking system inaccordance with an embodiment of the invention.

FIG. 2A is a conceptual illustration of an asset tracking device inaccordance with an embodiment of the invention.

FIG. 2B is a conceptual illustration of a remote server system inaccordance with an embodiment of the invention.

FIG. 3A is a flow chart illustrating a process for chaining assettracking devices in accordance with an embodiment of the invention.

FIG. 3B is a flow chart illustrating a process for determining thelocation of one or more asset tracking devices in accordance with anembodiment of the invention.

FIG. 3C is a flow chart illustrating a process for visualizing thelocation of one or more assets in accordance with an embodiment of theinvention.

FIG. 4 is a flow chart illustrating a process for filtering unchainedasset tracking devices in accordance with an embodiment of theinvention.

FIG. 5 is a flow chart illustrating a process for synchronizing assettracking devices in accordance with an embodiment of the invention.

FIG. 6 is a flow chart illustrating a process for minimizing power usageof chained asset tracking devices in accordance with an embodiment ofthe invention.

DETAILED DESCRIPTION

Turning now to the drawings, systems and methods for locating collocatedassets in accordance with embodiments of the invention are disclosed.Locating units can be used to identify the location of assets in avariety of location. Assets can include, but are not limited to,vehicles (e.g. automobiles, tractors, etc. . . . ) and non-locomotiveassets (cargo containers, trailers, etc.). Large numbers of assets areoften collocated in the same place, such as a storage yard or dockingfacility, and locating a particular asset can be quite difficult. Forexample, assets can be tracked using a Global Positioning System (GPS)receiver. However, it is well known that a GPS receiver has a locationaccuracy of approximately fifteen meters, which can narrow the locationof an asset to a particular area but is often not precise enough tolocate a specific asset, particularly when assets are stacked together.This problem is further compounded when assets are in transit within theyard. Other locating units, such as RFID tags, can also be employed tolocate an asset by using an interrogator to activate the locatingdevices installed on and identifying an asset. However, these locatingunits suffer from similar problems, particular when assets are inmotion.

Asset tracking devices in accordance with embodiments of the inventioncan be utilized to track a variety of vehicles and/or assets,particularly in environments where a large number of assets are stored.An asset tracking device can include a variety of communication devicesand/or sensor devices. Communication devices can include, but are notlimited to, radio transmitters (e.g. a RFID tag, a radio beacon, and/ora Bluetooth beacon) and network communication devices (e.g. a cellularmodem). Sensor devices can include, but are not limited, to,input-output (I/O) interfaces, location determination devices (e.g. aGPS receiver), and vehicle diagnostic interfaces. In a variety ofembodiments, an asset tracking device can be connected to a diagnosticconnector (e.g. an OBD II port) in a vehicle. It should be noted thatthe asset tracking device affixed to a particular asset can include adifferent hardware configuration for the particular asset being tracked.For example, an asset tracking device designed to be installed in avehicle can include a GPS receiver, radio transmitter, and cellularmodem and be powered by the vehicle's electrical system, while an assettracking device affixed to a cargo container may include a battery and alow-power radio transmitter. However, any configuration of hardware canbe utilized as appropriate to the requirements of specific applicationsof embodiments of the invention. The asset tracking devices can receiveperiodic signals from other asset tracking devices in their vicinity andmeasure the strength of the received signals along with recording theasset tracking device ID data provided in the periodic signals. Therelative position of each asset tracking device can be determined basedon the received signal strengths as described in more detail below. In avariety of embodiments, a master asset tracking device can then reportits location, along with the location of other asset tracking deviceschained to (i.e. grouped with) the master asset tracking device, to aremote server system.

As described above, a variety of assets may be in proximity to eachother but not be chained together. Asset tracking devices in accordancewith embodiments of the invention can employ a variety of processes tofilter asset tracking devices that are within the range of a masterasset tracking device but are not associated with an asset in the set ofchained assets. In this way, the location of a number of assets can beaccurately tracked by filtering unchained assets from the set of chainedassets. In several embodiments, one or more asset tracking devices in agroup can dynamically determine a master asset tracking device for thegroup as described in more detail below.

In a variety of embodiments, the operational state of a vehicle isutilized in determining if an asset tracking device can be a masterasset tracking device for a group. In a number of embodiments, vehicleignition state (i.e. the operational status of the vehicle) isascertained by monitoring the vehicle for signs indicative of thevehicle ignition state without directly connecting to the vehicleignition line. Information indicative of vehicle ignition state (i.e.vehicle status data) can be ascertained by observing characteristics ofthe vehicle including but not limited to the power supplied by thevehicle, vehicle vibration, communications on an OBD II or other vehicledata bus line, and/or vehicle position information. In many embodiments,multiple different types of information are combined to ascertain thevehicle ignition state. Systems and methods for using an asset trackingdevice added to the vehicle after the manufacture of the vehicle withouta direct connection to the vehicle ignition line that can be utilized todetermine ignition state information in accordance with embodiments ofthe invention are described in U.S. Pat. No. 8,489,271, titled “Systemsand Methods for Virtual Ignition Detection” and issued Jul. 16, 2013,the disclosure of which is hereby incorporated by reference in itsentirety.

In accordance with many embodiments of the invention, asset trackingdevices can include one or more sensors capable of determining the speedand/or acceleration of the tracked asset. Vehicle speed can becalculated using information provided by a Global Position System (GPS)receiver by dividing the distance traveled by the GPS receiver by thetime between measurements taken by the GPS receiver. In severalembodiments, the GPS receiver determines velocity information using thesignals received by the GPS receiver. A GPS receiver can determinevelocity information in a variety of ways in accordance with embodimentsof the invention, including, but not limited to, measuring the Dopplershift of the received signals. The differences in speed betweenmeasurements taken by the GPS receiver can be used to determineacceleration data for the tracked asset. GPS receivers are also capableof determining the location and/or the heading of the asset utilizingthe received signals. A variety of devices other than GPS receivers canbe utilized in vehicles to determine information related to the vehicle,such as speed, acceleration, and heading. For example, accelerationinformation for an asset can be measured using an accelerometer whileheading information can be determined using a compass. Vibrationinformation can be determined using acceleration information taken usingan acceleration sensor. In several embodiments, asset tracking devicesare calibrated to accurately determine speed and/or acceleration data.Systems and methods for calibrating a 3-axis accelerometers that can beutilized to determine vibration information in accordance with a varietyof embodiments of the invention are disclosed in U.S. Pat. No.9,217,757, titled “Systems and Methods for 3-Axis AccelerometerCalibration” and issued Dec. 22, 2015, the entirety of which is herebyincorporated by reference.

Systems and methods for tracking assets using asset tracking devices inaccordance with embodiments of the invention are described in moredetail below.

Asset Tracking Systems

Asset tracking systems in accordance with embodiments of the inventioncan accurately determine the location of a variety of locomotive andnon-locomotive assets by dynamically determining when particular assetsare chained together. A conceptual diagram of an asset tracking systemin accordance with an embodiment of the invention is shown in FIG. 1.The asset tracking system 100 includes a master asset tracking device110 in communicating with a remote server system 130 and a variety ofchained asset tracking devices 112 in communication with the masterasset tracking device 110. In a variety of embodiments, the master assettracking device 110 communicates with the remote server system 130 via anetwork 120. In a variety of embodiments, the network 120 is theInternet. In many embodiments, the network 120 is any wired or wirelessnetwork, such as a cellular network, between the master asset trackingdevice 110 and the remote server system 130. In a number of embodiments,the remote server system 130 implemented using a single server system.In several embodiments, the remote server system 130 is implementedusing multiple server systems.

In a variety of embodiments, the master asset tracking device 110 and/orthe chained asset tracking devices 112 is installed in a vehicle havinga vehicle data bus. In several embodiments, the asset tracking devicesare connected to a vehicle diagnostic connector that provides access tothe vehicle data bus. The asset tracking devices can obtain data fromany of a variety of vehicle devices connected to the vehicle data busutilizing any of a variety of techniques as appropriate to therequirements of specific applications of embodiments of the invention.Vehicle devices can include, but are not limited to, engine sensors,electronic control unit (ECU) devices, alternator sensors, vibrationsensors, voltage sensors, oxygen sensors, Global Positioning System(GPS) receivers, ignition devices, weight sensors, and/or accelerationdetermination devices. Systems and methods for connecting to a vehicledata bus that can be utilized in accordance with embodiments of theinvention are described in SAE J1978, titled “OBD II Scan Tool,” firstpublished by SAE International of Troy, Mich. on Mar. 1, 1992 and lastupdated Apr. 30, 2002. Systems and methods for obtaining data fromdevices connected to a vehicle data bus are described in SAE J1979,titled “E/E Diagnostic Test Modes,” first published by SAE Internationalon Dec. 1, 1991 and last updated Aug. 11, 2014. The disclosures of SAEJ1978 and SAE J1979 are hereby incorporated by reference in theirentirety. In a number of embodiments, the asset tracking devices areconnected directly to one or more sensors within an asset and/or doesnot utilize a vehicle data bus.

Asset tracking devices can include any of a variety of sensors and/ordevices, including those described above with respect to the vehicledata bus and those described in more detail below, to obtain dataregarding the status of the vehicle. This data can be utilized in avariety of location determination processes to determine the location ofone or more assets as described in more detail below. Asset trackingdevices can also communicate with any of a variety of sensors and/ordevices (such as other asset tracking devices) using an input-output(I/O) interface. I/O interfaces can be any connection, including wiredand wireless connections, as appropriate to the requirements of specificapplications of embodiments of the invention. In a variety ofembodiments, the I/O interface includes a low-power radio frequencytransceiver, such as a Bluetooth Low Energy radio. In severalembodiments, asset tracking devices are capable of executing scripts toread data and/or perform particular processes. These scripts can bepre-loaded on the device and/or obtained from the remote server system130, vehicle data bus, and/or the I/O interface as appropriate to therequirements of specific applications of embodiments of the invention.Asset tracking devices can be self-powered and/or connected into theelectrical system of the vehicle (or other asset) in which the assettracking device is installed. In a variety of embodiments, the assettracking device is powered via a vehicle data bus and/or a I/Ointerface. In many embodiments, asset tracking devices utilize a GlobalPositioning System (GPS) receiver in order to determine the location,speed, and/or acceleration of the asset in which the asset trackingdevice is installed. However, it should be noted that anylocation-determining techniques, such as cellular tower triangulation,wireless network geolocation techniques, and dead reckoning techniques,could be utilized as appropriate to the requirements of specificapplications of embodiments of the invention.

In a variety of embodiments, asset tracking devices and/or the remoteserver system 130 provides a user interface allowing for visualizing andinteracting with the data. In several embodiments, the asset trackingdevices and/or remote server system 130 provides an interface, such asan application programming interface (API) or web service that providessome or all of the data to third-party systems for further processing.Access to the interface can be open and/or secured using any of avariety of techniques, such as by using client authorization keys, asappropriate to the requirements of specific applications of theinvention.

Although a specific architecture of an asset tracking system inaccordance with embodiments of the invention are discussed above andillustrated in FIG. 1, a variety of architectures, including sensors andother devices and techniques not specifically described above, can beutilized in accordance with embodiments of the invention. Furthermore,the processes described herein can be performed using any combinationthe asset tracking devices and/or the remote server systems asappropriate to the requirements of specific applications of embodimentsof the invention.

Asset Tracking Devices and Remote Server Systems

Asset tracking devices in accordance with embodiments of the inventioncan dynamically chain themselves together based on the proximity oftheir associated assets and calculate the location of those assets. Aconceptual illustration of an asset tracking device in accordance withan embodiment of the invention is shown in FIG. 2A. The asset trackingdevice 200 includes a processor 210 in communication with memory 230.The asset tracking device 200 can also include one or more communicationdevices 220 capable of sending and receiving data. In a number ofembodiments, the communication devices 220 are in communication with theprocessor 210, the memory 230, and/or the sensor device(s) 240. Inseveral embodiments, the memory 230 is any form of storage storing avariety of data, including, but not limited to, a locating trackingapplication 232, location data 234, asset data 236, and/or signalstrength data 238. In many embodiments, the locating trackingapplication 232, location data 234, asset data 236, and/or signalstrength data 238 are stored using an external server system andreceived using the communication devices 220. Sensor devices 240 caninclude RPM sensors, voltage sensors, GPS receivers, noise sensors,vibration sensors, acceleration sensors, weight sensors, and any otherdevice capable of measuring data regarding an asset as appropriate tothe requirements of specific applications of embodiments of theinvention. Sensor devices 240 can be included within the asset trackingdevice 200 and/or located external to the asset tracking device 200. Theasset tracking device 200 can communicate with external sensor devicesusing the communication devices 220, such as via a vehicle data bus, RFconnection, and/or a network connection as appropriate to therequirements of specific applications of embodiments of the invention.

Remote server systems in accordance with embodiments of the inventioncan request, obtain, and track data regarding the location of one ormore assets. A conceptual illustration of a remote server system inaccordance with an embodiment of the invention is shown in FIG. 2B. Theremote server system 250 includes a processor 252 in communication withmemory 260. The remote server system 250 can also include one or morecommunication interfaces 254 capable of sending and receiving data. In anumber of embodiments, the communication interface 254 is incommunication with the processor 252 and/or the memory 260. In severalembodiments, the memory 260 is any form of storage configured to store avariety of data, including, but not limited to, an asset trackingapplication 262, tracked asset data 264, and/or geographic data 266. Inmany embodiments, the asset tracking application 262, tracked asset data264, and/or geographic data 266 are stored using an external serversystem and received by the remote server system 250 using the I/Ointerface 254.

The processor 210 and processor 252 can be directed, by the locationtracking application 232 and the asset tracking application 262respectively, to perform a variety of asset tracking processes. A numberof asset tracking processes that can be performed in accordance withembodiments of the invention are described in more detail below.

Although specific architectures for asset tracking devices and remoteserver systems in accordance with embodiments of the invention areconceptually illustrated in FIGS. 2A-B, any of a variety ofarchitectures, including those that store data or applications on diskor some other form of storage and are loaded into memory at runtime, canalso be utilized. Additionally, any of the data utilized in the systemcan be cached and transmitted once a network connection (such as awireless network connection via the communications device or I/Ointerface) becomes available. In a variety of embodiments, a memoryincludes circuitry such as, but not limited to, memory cells constructedusing transistors, that are configured to store instructions. Similarly,a processor can include logic gates formed from transistors (or anyother device) that dynamically perform actions based on the instructionsstored in the memory. In several embodiments, the instructions areembodied in a configuration of logic gates within the processor toimplement and/or perform actions described by the instructions. In thisway, the systems and methods described herein can be performed utilizingboth general-purpose computing hardware and by single-purpose devices.

Chaining and Locating Asset Tracking Devices

A number of asset tracking processes include dynamically chaining (i.e.grouping) a number of assets together based on the proximity of thoseassets to each other. For example, a number of cargo containers can beattached to a tractor and moved throughout a storage yard. The tractorsand the attached cargo containers can constitute a set of chainedassets. Similarly, a number of assets stored in the same section of awarehouse can constitute a set of chained assets. Each of the assets canbe associated with at least one asset tracking device. Asset trackingdevices can transmit and receive signals including asset dataidentifying the asset tracking device and/or asset. The strength of thereceived signals can be measured and signal strength data describing thereceived signal strength along with the corresponding asset data can begenerated. The asset tracking devices can collect the asset data andsignal strength data and report the collected data along with its ownasset data to a central device, such as a master asset tracking deviceor a remote server system, as appropriate to the requirements ofspecific applications of embodiments of the invention.

Asset tracking processes can also include determining the location ofone or more assets based on the location of the asset tracking deviceassociated with the particular asset. A central device can calculate therelative position of each asset tracking device in a particular set ofchained asset tracking device based on the reported signal strength datafor each of the chained asset tracking devices. That is, the relativelocation of a first asset tracking device from a second asset trackingdevice can be calculated based on the frequency of the signaltransmitted from the first asset tracking device to the second assettracking device, the broadcast strength of the signal, and/or thestrength of that signal as received by the second asset tracking device.In several embodiments, the relative location can also be calculatedbased on the geometry of the antenna used to transmit and/or receive thesignal, radiation resistance, and any other factors as appropriate tothe requirements of specific applications of embodiments of theinvention. In many embodiments, one or more of the asset trackingdevices obtain location data describing its location, such as by using aGPS receiver to determine its location. The set of chained assettracking devices can then be utilized to determine a set of chainedassets, where the chained assets include those assets associated withthe chained asset tracking devices.

In addition to determining which assets are chained together, the signalstrength data and/or relative location information can be utilized todetermine a relative ordering of assets within a set of chained assets.For example, two or more trailers may be hooked in series to a singletractor and be moving through a storage facility. In this example, itcan be important to know which trailer is at the end of the chain asthat trailer will need to be decoupled from the set of chained assetsbefore assets nearer to the tractor can be accessed. In manyembodiments, the relative ordering of the assets within a set of chainedassets can be determined relative to a master asset tracking devicebased on the received signal strength for each of the asset trackingdevices attached to the assets. By ordering the asset tracking devicesby received signal strength, the asset tracking device with the weakestreceived signal strength is likely associated with the asset at the endof the set of chained assets. Similarly, the asset tracking devicehaving the strongest received signal strength is likely closest to themaster tracking device and therefore at the start of the set of chainedassets. However, it should be noted that, in a variety of embodiments,the material and/or construction of an asset and/or any of the factorsaffecting signal strength described above can have an effect on thereceived signal strength for the particular asset tracking device forthat asset. It should be noted that any of a variety of weightings canbe applied to the received signal strength to correct for these issuesin order to refine the ordering of asset tracking devices by receivedsignal strength as appropriate to the requirements of specificapplications of embodiments of the invention.

Turning now to FIG. 3A, a process for chaining asset tracking devices inaccordance with an embodiment of the invention is shown. The process 300includes obtaining (310) asset signal data, calculating (312) assetsignal strength, determining (314) aggregate signal strength data, and,in many embodiments, transmitting (316) aggregate signal strength dataand/or determining (318) asset position data.

The relative location of one asset tracking device to another assettracking device, as described above, can be used to define a circularregion with a radius of the distance between the two asset trackingdevices. That is, the received signal strength can be used to indicate aset of potential locations for the asset tracking devices, but may notprovide the absolute location of the asset tracking devices given thedistance. However, a variety of processes can be utilized in accordancewith embodiments of the invention to determine the absolute location ofan asset tracking device given the relative location. In a variety ofembodiments, one or more asset tracking devices are fixed in a knownposition. These fixed asset tracking devices can be utilized to providean absolute location for a particular asset tracking device using any ofa variety of location determination techniques, such as locationtriangulation, as appropriate to the requirements of specificapplications of embodiments of the invention. In several embodiments,the signal strength for a particular asset tracking device can bereceived from two or more other asset tracking devices in the set ofchained asset tracking devices. These signal strengths can be utilizedto calculate a number of radial regions in which the particular assettracking device can be located relative to the other asset trackingdevices in the set of chained asset tracking devices. A variety oftechniques, such as multilateration or trilateration, can be utilized tocalculate the location of the asset tracking devices as appropriate tothe requirements of specific applications of embodiments of theinvention.

Turning now to FIG. 3B, a process for locating tracked assets inaccordance with an embodiment of the invention is shown. The process 350includes obtaining (360) aggregate signal strength data, calculating(362) relative asset position data, and determining (364) asset positiondata.

In many embodiments, the asset tracking processes include determiningasset position data by combining the asset position data with geographicdata describing the geography of a particular region, such as a storagefacility. However, it should be noted that any region can be describedusing the geographic data as appropriate to the requirements of specificapplications of embodiments of the invention. In a variety ofembodiments, the geographic data includes the location of fixed assettracking devices that can be utilized to determine absolute positiondata for one or more assets as described herein. In several embodiments,the geographic data and the asset position data can be utilized togenerate user interface data that can be used to visualize the locationof one or more assets within the geographic region.

Turning now to FIG. 3C, a process for visualizing the location of one ormore assets is shown. The process 380 includes obtaining (390)geographic data, obtaining (392) asset position data, and generating(394) asset visualization data.

Specific processes for chaining and locating asset tracking devicesalong with visualizing the associated assets in accordance withembodiments of the invention are described above and shown with respectto FIGS. 3A-C; however, any number of processes, including those thatutilize different combinations of data than the examples describedabove, can be utilized as appropriate to the requirements of a specificapplication in accordance with embodiments of the invention. Techniquesfor determining particular assets that have been grouped together inaccordance with embodiments of the invention are described in moredetail below.

Filtering Unchained Assets

Assets are often positioned in close proximity to one another such thatwhen a set of chained assets is in motion, the asset location devices ofadjacent or nearby assets (i.e. transient assets) can be picked up bythe asset location devices in the set of chained assets. Asset trackingprocesses in accordance with embodiments of the invention includeidentifying these nearby but unchained assets and filtering those assetsfrom the set of chained assets. That is, as the set of chained assetsmoves, the signal strength measurements reported to and collected by themaster asset tracking device will indicate relative consistency forthose asset tracking devices whose assets are part of the set of chainedassets and will indicate variations for those transient asset trackingdevices whose assets are not part of the set of chained assets. In thisway, low pass filters can be applied to the signals generated based onthe transience of the assets to identify those assets that are chainedand those that are transient.

Consistency in signal strength can be determined using a variety ofprocesses. For example, a master asset tracking device can maintaincounter data for each signal received indicating the number of times asignal from a particular asset tracking device is received. A thresholdvalue can be used to determine when the particular asset tracking devicehas been in proximity to the master asset tracking device for asufficient amount of time to determine that the assets have been chainedtogether. Those signals received by the master asset tracking devicethat do not have an associated counter exceeding the threshold value canbe considered to be associated with transient assets that are not partof the set of chained assets. Similarly, when the counter for aparticular asset tracking device exceeds the threshold value, theassociated asset can then be considered part of the set of chainedassets.

The determination of if an asset is transient can include tracking theelapsed time since a signal has been received from an asset trackingdevice. By way of example, a master asset tracking device can maintaintimestamp data describing when a signal is received from an assettracking device. The master asset tracking device can then use thetimestamps to determine when a particular asset tracking device has beenseen. A time-based threshold can be applied to the timestamp todetermine when a particular asset tracking device has not been seen fora period of time, indicating that it is not associated with an asset inthe set of chained assets. Likewise, those signals that have beenreceived within a certain period of time may indicate those assets thathave recently appeared and may be associated with assets that are notpart of the set of chained assets. In this way, a master asset trackingdevice can filter those devices that have been seen too recently (e.g.for less than five seconds) and/or not recently enough (e.g. for morethan 5 minutes) from the set of chained assets.

Threshold values utilized in the asset tracking processes can be fixedand/or determined dynamically based on any of a variety of factors,including (but not limited to) the transmission rate of the assettracking devices, the number of asset tracking devices in proximity, thespeed at which the asset tracking devices are moving, and/or thepresence of a synchronization signal as appropriate to the requirementsof specific applications of embodiments of the invention.

Turning now to FIG. 4, a process for filtering unchained assets inaccordance with an embodiment of the invention is shown. The process 400includes obtaining (410) asset signal data, calculating (412) assetsignal strength data, and determining (414) if particular assets aretransient. If an asset is identified as transient, it is filtered (416)from the database of chained assets.

Although specific processes for filtering unchained assets in accordancewith embodiments of the invention are described above and shown withrespect to FIG. 4, any number of processes, including those that usealternative criteria for determining if an asset is transient from theperspective of the asset tracking device, can be utilized as appropriateto the requirements of a specific application in accordance withembodiments of the invention.

Synchronizing Asset Tracking Devices

Assets that are present in a set of chained assets are often physicallyconnected. For example, many assets have lighting systems that areconnected together when the assets are chained. Asset tracking processesin accordance with embodiments of the invention can include determiningwhen assets are chained together based on synchronization data common tothe chained assets. In a variety of embodiments, synchronization datacan be included in the asset signal data. The master asset trackingdevice can then use the synchronization data to determine if aparticular asset tracking device is associated with a chained assetbased on the presentence and/or value of the synchronization data. Thesynchronization data can include any data captured from an asset, suchas voltage data, ignition state data, speed data, and/or any other dataas appropriate to the requirements of specific applications ofembodiments of the invention. In several embodiments, an asset trackingdevice includes one or more sensor devices that are coupled to systemswithin the asset in order to obtain data describing the state of thosesystems.

For example, a set of chained assets can have their brake lightingsystems connected so that when the brakes are applied on one asset itcauses the brake lights to activate on all of the connected assets. Anasset tracking device can be coupled to the brake lighting system withinthe assets using a sensor device (i.e. a sensor interface), therebyallowing the asset tracking devices to measure the voltage present inthe brake lighting system on each asset. The voltage of the brake lightsystem can be used as the synchronization data as each of the chainedassets will have their brake lights operating in concert. By way of asecond example, each asset tracking device can have a synchronizationcounter that (re)starts on receipt of the synchronization criteria (i.e.the brake light voltage of the instant example). The synchronizationdata can include the counter data and the master asset tracking devicecan compare the counter data received from a particular asset trackingdevice to its own counter to determine if the asset tracking devices areboth measuring the synchronization signal (i.e. the brake light voltagein the instant example). If the counters match (either exactly or withina threshold value), the assets are chained, otherwise if the counters donot match then the assets are not chained and the particular asset canbe filtered from the set of chained assets.

In several embodiments, the synchronization data can be utilized todetermine the relative ordering of assets within a set of chained assetsutilizing processes similar to those described above. For example, inembodiments using counters to determine if asset tracking devices aresynchronized, assets can be considered to be chained if their countersare within a threshold value of each other and the value of the counterscan be utilized to order the asset tracking devices. For example, asignal can be utilized to synchronize the counters and, due to a varietyof effects such as signal propagation delays, it is likely that theasset tracking devices located on assets near the end of the chain ofassets will initialize their counters at a later time than those assettracking devices associated with assets at the front of the chain ofassets. In this way, those asset tracking devices reporting lowercounter values (as the counter started later in time) are further awayfrom the master asset tracking devices than those asset tracking devicesreporting higher counter values. Similarly, in those embodimentsutilizing a voltage measurement, the asset tracking devices at the endof the chain can read a lower voltage than those asset tracking devicesat the beginning of the chain due to increased resistance as the lengthof the chain increases. However, it should be noted that anysynchronization data can be utilized to determine a relative ordering ofasset tracking devices (and their associated assets) within a set ofchained assets utilizing any of a variety of techniques as appropriateto the requirements of specific applications of embodiments of theinvention.

Turning now to FIG. 5, a process for synchronizing asset trackingdevices in accordance with an embodiment of the invention is shown. Theprocess 500 includes obtaining (510) synchronization data, obtaining(512) asset signal data, and determining if asset signal data issynchronized (514). If the asset signal data is not synchronized (514),the identified asset is filtered (516).

Although specific processes for synchronizing asset tracking devices inaccordance with embodiments of the invention are described above andshown with respect to FIG. 5, any number of processes, including thosethat utilize alternative data to synchronize asset tracking devices, canbe utilized as appropriate to the requirements of a specific applicationin accordance with embodiments of the invention.

Improving Asset Tracking Device Performance

If assets are traveling together as a group, it can be more efficientfor a single asset tracking device to maintain the group's positionand/or provide the location data to a remote server system over a widearea network than it is for each asset location device to report its ownposition and/or collect absolute positioning data. Asset trackingprocesses in accordance with embodiments of the invention can includedetermining master asset tracking devices to provide centralizedreporting of location data for the set of chained assets. In a varietyof embodiments, for a set of asset tracking devices, the responsibilityof the master asset tracking device for the set can be spread around theentire population of the set to distribute battery consumption acrossthe asset tracking devices. Any of a variety of techniques, such asround robin selection processes, processes utilizing the remainingbattery power of one or more asset tracking devices, and processes thatselect a master asset tracking device based on the capabilities of theasset tracking devices can be utilized as appropriate to therequirements of specific applications of embodiments of the invention.In several embodiments, a single device is selected as the master assettracking device for the set of asset tracking devices.

For example, a master asset tracking device can utilize a GPS receiverto determine absolute location data. By utilizing a single mastertracking device, the time and power overhead of the GPS positiondetermination processes need not be repeated on multiple devices,thereby reducing the power consumption of the set as a whole. By way ofa second example, a first asset tracking device may be installed in anasset having a large power supply (such as a tractor having a vehiclebattery and/or alternator). Other asset tracking devices in the set canbe deployed on assets lacking such power supplies, such as trailers.These asset tracking devices can utilize lower power radios and/or notinclude higher power components such as GPS receivers and cellularradios. In this example, the first asset tracking device can be selectedas the master asset tracking device due to its location on a poweredasset and/or its location determination capabilities based on its GPSreceiver.

However, it should be noted that any asset tracking device in the set ofasset tracking devices can be selected as the master asset trackingdevice. In many embodiments, multiple asset tracking devices aresimultaneously selected as master asset tracking devices for the entireset. For example, one asset tracking device can be selected as a masterasset tracking device to determine absolute location data while a secondasset tracking device can be selected as a master asset tracking deviceto report data to a remote server system. It should be noted that anycriteria can be utilized to select one or more master asset trackingdevices as appropriate to the requirements of specific applications ofembodiments of the invention.

Turning now to FIG. 6, a process for improving the performance of assettracking devices in accordance with an embodiment of the invention isshown. The process 600 includes obtaining (610) asset data, obtaining(612) location data, providing (614) data, and determining (616) amaster asset tracking device.

Specific processes for improving the performance of asset trackingsystems and asset tracking devices in accordance with embodiments of theinvention are described above and shown with respect to FIG. 6; however,any number of processes, including those that utilize alternativecriteria for selecting a master asset tracking device and/or those thatreceive data configuring an asset tracking device to act as the masterasset tracking device from a remote server system, can be utilized asappropriate to the requirements of a specific application in accordancewith embodiments of the invention.

Although the present invention has been described in certain specificaspects, many additional modifications and variations would be apparentto those skilled in the art. In particular, any of the various processesdescribed above can be performed in alternative sequences and/or inparallel (on the same or on different computing devices) in order toachieve similar results in a manner that is more appropriate to therequirements of a specific application. It is therefore to be understoodthat the present invention can be practiced otherwise than specificallydescribed without departing from the scope and spirit of the presentinvention. Thus, embodiments of the present invention should beconsidered in all respects as illustrative and not restrictive. It willbe evident to the person skilled in the art to freely combine several orall of the embodiments discussed here as deemed suitable for a specificapplication of the invention. Throughout this disclosure, terms like“advantageous”, “exemplary” or “preferred” indicate elements ordimensions which are particularly suitable (but not essential) to theinvention or an embodiment thereof, and may be modified wherever deemedsuitable by the skilled person, except where expressly required.Accordingly, the scope of the invention should be determined not by theembodiments illustrated, but by the appended claims and theirequivalents.

What is claimed is:
 1. An asset tracking device, comprising: aprocessor; a memory connected to the processor; and a communicationsdevice connected to the processor; wherein the processor: obtains assetsignal data, where the asset signal strength data comprises asset dataidentifying an asset; calculates asset signal strength data based on theobtained asset signal data; and determines chained asset data based onthe asset signal data and the asset signal strength data, where thechained asset data identifies a set of assets chained to a master assetassociated with the asset tracking device.
 2. The asset tracking deviceof claim 1, wherein the processor determines the location of the assetrelative to the asset tracking device based on the asset signal strengthdata.
 3. The asset tracking device of claim 1, wherein: the assettracking device further comprises a location determination deviceconnected to the processor; and the processor further determinesabsolute location data using the location determination device.
 4. Theasset tracking device of claim 3, wherein the processor furtherdetermines the absolute location of the asset based on the absolutelocation data and the asset signal strength data.
 5. The asset trackingdevice of claim 1, wherein the processor further transmits the chainedasset data to a remote server system using the communications device. 6.The asset tracking device of claim 1, wherein the communications devicecomprises a cellular modem.
 7. The asset tracking device of claim 1,wherein: the communications device comprises a radio frequencytransceiver; and the asset signal data is received using thecommunications device.
 8. The asset tracking device of claim 7, whereinthe radio frequency transceiver comprises a Bluetooth Low Energy radio.9. The asset tracking device of claim 1, wherein: the asset signal datafurther comprises synchronization data; and the processor determines thechained asset data based on the synchronization data.
 10. The assettracking device of claim 9, wherein the synchronization data comprisesbrake lighting system voltage data.
 11. The asset tracking device ofclaim 9, wherein the synchronization data comprises counter data. 12.The asset tracking device of claim 1, wherein: the asset tracking devicecomprises a diagnostic connector; and the asset tracking device isconnected to a vehicle diagnostic connector in an asset.
 13. An assettracking system, comprising: a set of asset tracking devices, whereineach asset tracking device comprises a processor, a memory connected tothe processor, and a communications device; and wherein at least oneasset tracking device in the set of asset tracking devices: transmitsasset signal data; obtains asset signal data from at least one assettracking device in the set of asset tracking devices; determinesaggregate signal strength data for each of the other asset trackingdevices in the set of asset tracking devices based on the obtained assetsignal data; and calculates asset position data for every other assettracking device in the set of asset tracking devices based on theaggregate signal strength data.
 14. The asset tracking system of claim13, wherein: each asset tracking device in the set of asset trackingdevices is associated with an asset; each asset tracking device in theset of asset tracking devices is connected to a synchronization signalon its associated asset; and the asset signal data comprisessynchronization data determined based on the synchronization signal. 15.The asset tracking system of claim 13, wherein: a master asset trackingdevice in the set of asset tracking devices further comprises a locationdetermination device; and the master asset tracking device: determinesabsolute position data describing the location of the master assettracking device using the location determination device; and determinesasset position data describing the location of the other asset trackingdevices in the set of asset tracking devices based on the absoluteposition data and the asset position data.
 16. The asset tracking systemof claim 15, wherein the master asset tracking device further transmitsthe asset position data to a remote server system.
 17. The assettracking system of claim 13, wherein: the communication device comprisesa low power radio frequency transceiver; and each asset tracking devicein the set of asset tracking devices transmits the asset signal datausing the communications device.
 18. A method for determining thelocation of an asset, comprising: obtaining asset signal data using anasset tracking device, where the asset signal strength data comprisesasset data identifying an asset and the asset tracking device comprisesa processor, a memory connected to the processor, and a communicationsdevice; calculating asset signal strength data based on the obtainedasset signal data using the asset tracking device; and determiningchained asset data based on the asset signal data and the asset signalstrength data using the asset tracking device, where the chained assetdata identifies a set of assets chained to a master asset associatedwith the asset tracking device.
 19. The method of claim 18, furthercomprising determining relative location data for the asset based on theasset signal strength data using the asset tracking device.
 20. Themethod of claim 18, further comprising transmitting the chained assetdata to a remote server system using the asset tracking device.